Thank you, Mark, your explanation clears up a lot of misunderstandings I had about the gurgling question. One more: If you gurgle you're emptying your oil suction side. Why would you want to do that? Surely the engine is lubricated quicker after start-up with the suction piping filled?
I replaced the oil, oil filter, fuel and fuel filter. I checked the pistons and sleeves as well as I could through the spark plug hole. Which wasn't really very good. There is a thin layer of deposits on the cylinders, but it looks like it is coming off, instead of being a result of the diesel. The spark plugs look brand new. After 27 hours I would have expected them to look worse. The test flight was perfect, with everything, including my confidence in the engine, in the green.
Blue skies
Arthur
